There are many possible causes of laminitis but the vast majority of cases have a hormonal/endocrine root. There is a peak in the spring, related to grazing young high sugar growths of grass. A second peak occurs in the fall, but the cause is more complicated.
Spring laminitis cases are often grass related but fall is more complicated.
Grass does undergo a period of regrowth in the fall in some areas, but many cases of fall laminitis aren’t even on pasture. There is a natural rise in the hormone ACTH from late summer through end November in all horses. ACTH stimulates release of cortisol.
In older horses and horses that are early cases of Cushing’s Disease this rise can be very exaggerated and causes or worsens insulin resistance, often pushing the horses into laminitis. Reversing this means attacking both on the dietary end and also using medication, pergolide, to control exaggerated ACTH release.
Insulin resistance is managed with the same dietary adjustments whether it is a primary insulin resistance built into the horse’s genetic makeup or caused by hormonal changes with Cushing’s disease. The horse should be fed primarily grass hay with a combined sugar (ESC) and starch level below 10%. A good starting point is to feed 2% (20 pounds per 1000 lbs) of ideal body weight or 1.5% of current body weight, whichever is larger. This can be adjusted up or down to maintain a lean body weight but do NOT starve the horse.
There are several vitamins and minerals that play key roles in insulin function. Keeping mineral intakes at correct levels and balanced is one thing completely within our power to control. Ideally, supplementation is based on the results of hay analysis. If that is not possible, regional average analysis figures are often available.
For example, it has been well documented that normal magnesium status is important to maintaining cellular sensitivity to insulin.
Avoid supplements with any added iron in the ingredients list (look for both iron and ferric). Also check for mono and dicalcium phosphate in the ingredients list. Those minerals are typically very heavily contaminated with iron. Iron is already adequate if not excessive in virtually all hays. IR horses not on mineral balanced diets can be iron overloaded. Iron has been shown to worsen IR.
Hays from many areas are also deficient in copper and/or zinc but with adequate to high manganese so most people need a supplement to correct that – i.e. low to no manganese. These trace minerals can compete with each other for absorption.
Vitamin E is needed because this vitamin is always deficient in hay. Feed 2 IU (international units) per pound of body weight daily. Vitamin E requires fat for absorption so either use a liquid E in oil or mix a powdered E into some oil before feeding it.
Hooves recovering from laminitis need balanced minerals too, as well as adequate protein. Biotin supplementation supports hoof growth and pyridoxine is needed for amino acid/protein metabolism. The hoof wall is composed almost entirely of protein. Nitric oxide production inside blood vessels counteracts hoof blood vessel constriction that can occur with IR and Cushing’s. Jiaogulan provides potent support for nitric oxide production in the vessels.
There is no quick fix or magic bullet to prevent or reverse laminitis linked to hormonal disruption. Even pergolide can’t do the job on its own. Fortunately, the nutritional tools needed to win this battle are available to anyone who takes the time to learn what is needed and implement it.
Eleanor Kellon, VMD